He was born on 8 September 1912 the only child of Francis and Martha Mackendrick who had emigrated to the United States from Glasgow in 1911. His father was a ship builder and a civil engineer. When Mackendrick was six, his father died of influenza as a result of an pandemic that swept the world just after World War I. His mother, in desperate need of work, decided to be a dress designer. In order to pursue that decision, it was necessary for Martha MacKendrick to hand her only son over to his grandfather, who took young MacKendrick back to Scotland when he was seven years old. Mackendrick never saw or heard from his mother again.

Mackendrick had a sad and lonely childhood.[1] He attended Hillhead High School from 1919 to 1926 and then went on to spend three years at the Glasgow School of Art. In the early 1930s, MacKendrick moved to London to work as an art director for the advertising firm J. Walter Thompson. Between 1936 and 1938, Mackendrick scripted five cinema commercials. He later reflected that his work in the advertising industry was invaluable, in spite of his extreme dislike of the industry itself. MacKendrick wrote his first film script with his cousin and close friend, Roger MacDougall. It was bought by Associated British and later released, after script revisions, as Midnight Menace (1937).[1]

After the war, Mackendrick and Roger MacDougall set up Merlin Productions, where they produced documentaries for the Ministry of Information. Merlin Productions soon proved financially unviable. In 1946 Mackendrick joined Ealing Studios, originally as a scriptwriter and production designer, where he worked for nine years and directed five films made at Ealing; Whisky Galore! (US: Tight Little Island, 1949), The Man in the White Suit (1951), Mandy (1952), The Maggie (US: High and Dry, 1954) and The Ladykillers (1955), the first two and the last being among the best known of Ealing's films.[1]

Mackendrick often spoke of his dislike of the film industry and decided to leave the United Kingdom for Hollywood in 1955.[3] When the base of Ealing studios was sold that year, Mackendrick was cut loose to pursue a career as a freelance director, something he was never prepared to do:

"At Ealing ... I was tremendously spoiled with all the logistical and financial troubles lifted off my shoulders, even if I had to do the films they told me to do. The reason why I have discovered myself so much happier teaching is that when I arrived here after the collapse of the world I had known as Ealing, I found that in order to make movies in Hollywood, you have to be a great deal-maker ... I have no talent for that ... I realised I was in the wrong business and got out."[4]

The rest of his professional life was spent commuting between London and Los Angeles. His first film after his initial return to the United States was Sweet Smell of Success (1957), produced by Hecht-Hill-Lancaster Productions (HHL). This was a critically successful film about a press agent (Tony Curtis) who is wrapped up in a powerful newspaper columnist’s (Burt Lancaster) plot to end the relationship between his younger sister and a jazz musician. Mackendrick got along poorly with the producers of the film because they felt that he was too much of a perfectionist. After Sweet Smell of Success, he went back to England to make the second HHL film, The Devil’s Disciple (1959), but he was fired a month into production owing to lingering tension from their first project together. Mackendrick was devastated. In the same period, Mackendrick assisted Dutch film maker Bert Haanstra with the production of the comedy film, Fanfare (1958).

In an interview[6] he said, "Hearing the lines, hearing the playing of the lines in your mind’s ears, and seeing the performance in your mind’s eye, is the essence of filmmaking. The other thing—getting it on the screen—is the medium; film begins between the ears and under the hair of one character, and ends between the ears and under the scalpel of the audience."

"I've concentrated most of my energies on this particular program, which I like very much indeed, which is to take the make-believe of acting and working with actor, and requiring people who will develop behind the camera to be in front of the camera, requiring the directors to learn about working with actors, by being actors, by knowing what it means to be inside the skin of an actor", he said in his interview.[6]

"Imagination after all is the making of images. In the case of dramatic imagination it means the capacity to see an image from this point-of-view and then switch to another point-of-view. Without that playfulness of leaping points of view, you don’t have somebody who has the impulse to become a dramatic writer", he said in his interview.[6]

"It is really essential for the director, who is going to work with actors, to have attempted acting and to have learned the problems of the actor from inside, from the actor’s point-of-view and not the director’s point-of-view. Because you’ll learn things there, what you must never again do to an actor… I think the directors who are insensitive to the performers are really bad directors", he said in his interview.[6]

Once a student persistently asked him,[6] "How do you get an actor to do what you want?" After persuasion he replied, "You don’t. You get an actor to want what you need. What the director must do is, provide the actor with the encouragement to be what the director needs him to be. There is a reason why you are doing this. It is simple, almost too simple.

What you do as a director is that you fall in love with the actor in the role. Note that I say, in the role. You’ve got to get yourself infatuated, to a degree that you find yourself besottedly adoring the actor while he is inside the role, as you feel it… If the actor moves outside [the role], what you do, consciously or unconsciously, is you dim the beams of your love, and the actor feels cold and they move back into your love. It is emotional blackmail, on a very good cause. [Hence] before you can control an actor, the thing that you have to control is your self and your own feelings."